BZ:1924176 - Replacing DNS name servers #30283
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| = Modifying the DNS name servers | ||
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| You can override the DNS name servers and search list in the `/etc/resolv.conf` file. | ||
| Some operating systems use `NetworkManager` to manage network interfaces. |
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I think this applies to RHEL and Red Hat Core OS, so for our purposes, this is probably always true.
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The other text on the page mentioned "operating systems" generally more often that RHEL or RHCOS specifically, so I went with the more frequent use so this new topic would blend.
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| You can override the DNS name servers and search list in the `/etc/resolv.conf` file. | ||
| Some operating systems use `NetworkManager` to manage network interfaces. | ||
| When `NetworkManager` manages some interfaces, it also manages the contents of the `/etc/resolv.conf` file. |
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It might be worth checking RHEL docs, but I think it goes by just NetworkManager without italics.
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I'm using backticks based on the guidance for a daemon, service, or software package.
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| [source,terminal] | ||
| ---- | ||
| $ oc debug node/${ONE_HOST} -- chroot /host cat /etc/resolv.conf |
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I don't know if it's helpful to users or not, but I've always defined any variables used in a command, even if it ought to be obvious:
[source,terminal]
----
$ oc debug node/${ONE_HOST} -- chroot /host cat /etc/resolv.conf
----
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where:
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`ONE_HOST`:: Specifies the host name captured in the previous command.
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| [source,terminal] | ||
| ---- | ||
| $ cat << EOF | base64 |
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base64 with no options will cause line breaks every 77 characters to appear when the user copies and pastes it into their machine config which will cause errors. The user will have to delete the line breaks in order to remedy the errors. I prefer base64 -w0 which will not word wrap. The only caveat is that there is no line break at in the output before the next shell prompt. You can opt to do base64 -w99999999999999 which will add a line break at the very end as long as the base64 encoded output is not longer than 99999999999999 characters but this looks a little hacky.
Example: Without Option
[mnguyen@pet32 ~]$ cat << EOF | base64
# Custom resolv.conf added with Machine Config Operator
# and the override-etc-resolv-conf.yaml file.
search c.openshift-gce-devel-ci.internal google.internal c.openshift-gce-devel-ci.inte
nameserver 169.254.169.254
nameserver 8.8.8.8
EOF
IyBDdXN0b20gcmVzb2x2LmNvbmYgYWRkZWQgd2l0aCBNYWNoaW5lIENvbmZpZyBPcGVyYXRvcgoj
IGFuZCB0aGUgb3ZlcnJpZGUtZXRjLXJlc29sdi1jb25mLnlhbWwgZmlsZS4Kc2VhcmNoIGMub3Bl
bnNoaWZ0LWdjZS1kZXZlbC1jaS5pbnRlcm5hbCBnb29nbGUuaW50ZXJuYWwgYy5vcGVuc2hpZnQt
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LjguOC44Cg==
[mnguyen@pet32 ~]$
Example: With -w0 Option
[mnguyen@pet32 ~]$ cat << EOF | base64 -w0
# Custom resolv.conf added with Machine Config Operator
# and the override-etc-resolv-conf.yaml file.
search c.openshift-gce-devel-ci.internal google.internal c.openshift-gce-devel-ci.inte
nameserver 169.254.169.254
nameserver 8.8.8.8
EOF
IyBDdXN0b20gcmVzb2x2LmNvbmYgYWRkZWQgd2l0aCBNYWNoaW5lIENvbmZpZyBPcGVyYXRvcgojIGFuZCB0aGUgb3ZlcnJpZGUtZXRjLXJlc29sdi1jb25mLnlhbWwgZmlsZS4Kc2VhcmNoIGMub3BlbnNoaWZ0LWdjZS1kZXZlbC1jaS5pbnRlcm5hbCBnb29nbGUuaW50ZXJuYWwgYy5vcGVuc2hpZnQtZ2NlLWRldmVsLWNpLmludGUKbmFtZXNlcnZlciAxNjkuMjU0LjE2OS4yNTQKbmFtZXNlcnZlciA4LjguOC44Cg==[mnguyen@pet32 ~]$
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+1 to you,@mike-nguyen.
Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1924176 * From https://access.redhat.com/solutions/7412, configure NetworkManager not to update `/etc/resolv.conf`. * Follow the general guidance for replacing a file with the Machine Config Operator. * Feedback from jboxman and mike-nguyen.
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Engineering wants to take a different approach to this work. Abandoning. |
Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1924176
From https://access.redhat.com/solutions/7412, configure
NetworkManager not to update
/etc/resolv.conf.Follow the general guidance for replacing a file with
the Machine Config Operator.
Updates are at the following heading: https://deploy-preview-30283--osdocs.netlify.app/openshift-enterprise/latest/post_installation_configuration/machine-configuration-tasks.html#machineconfig-modify-dns-nameservers_post-install-machine-configuration-tasks
Note to self: This PR applies to 4.8 and 4.7. The Ignition config file version is 3.1 for 4.6.